1. Technical Field
The present invention relates to semiconductor lasers in general, and in particular to static semiconductor pump lasers. Still more particularly, the present invention relates to a method and apparatus for cooling static semiconductor pump lasers.
2. Description of the Related Art
A laser is capable of producing monochromatic, coherent light through the stimulated emission of photons from atoms, molecules or ions of an active gain medium by an input of energy. A laser includes a resonator that is typically defined by two highly reflecting surfaces for forming a closed round trip path for light to travel. The active gain medium is resided within the resonator.
If a population inversion is created by an excitation of the active gain medium, the spontaneous emission of a photon from an excited atom, molecule or ion undergoing transition to a lower energy state can stimulate an emission of photons of substantially identical energy from other excited atoms, molecules or ions. As a result, the initial photon creates a cascade of photons between the reflecting surfaces of the resonator that are of substantially identical energy and exactly in phase. A portion of the cascade of photons is then discharged out of the resonator, for example, by transmission through one of the two reflecting surfaces of the resonator. Such discharged photons constitute a laser output.
The excitation of an active gain medium within a laser can be accomplished by a variety of methods, with optical pumping being the most common. Recent advances in pump diode technology enables intensely bright fiber-based pump sources to be formed. Such fiber-based pump source is capable of delivering at lease 10 kW absorbed intensities. As a result, rare ion lasers can operate at near quasi-3 levels. At such absorbed energy densities, however, thermal aberrations increase to a point that will impact beam qualities and overall heating levels.
Many attempts have been made to provide a more intimate cooling path to avoid the above-mentioned problems, but none yields a satisfactory result. Consequently, it would be desirable to provide an improved method and apparatus for cooling high intensity pump lasers.